<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <script>
    let num1=10
    let num2=20
    document.write(num1,num2)
    let t
    t=num1
    num1=num2
    num2=t
    document.write()
    <br>
    document.write(num1,num2)
    
    
    </script>
</body>
</html>